Flash Flooding and Flooding in Hawaii, February 20 to 24, 2013

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
830 PM HST TUE FEB 19 2013

.SYNOPSIS...
STRONG TRADE WINDS CONTINUE TONIGHT ACROSS THE MAIN HAWAIIAN
ISLANDS AS A DOMINANT HIGH PRESSURE SYSTEM REMAINS FAR NORTH OF THE
AREA. CLOUDS AND SHOWERS WILL FAVOR WINDWARD AND MAUKA AREAS...WITH
SOME SHOWERS REACHING LEEWARD LOCATIONS AT TIMES. AN UPPER LEVEL
TROUGH TO THE NORTHEAST OF THE BIG ISLAND WILL BRING PERIODS OF
ENHANCED TRADE SHOWERS THROUGH THE WEEKEND.

&&

.DISCUSSION...
A SPRAWLING DOMINANT SFC HIGH PRESSURE SYSTEM REMAINS CENTERED FAR
N/NE OF THE ALOHA STATE AND KEEPING TIGHT PRESSURE GRADIENTS ACROSS
THE AREA. ALTHOUGH THE WIND ADVISORY WAS CANCELLED FROM MOLOKAI TO
KAUAI...EXPECT BREEZY CONDITIONS WITH PERIODS OF WIND GUSTS IN THE
30 TO 40 MPH RANGE TO CONTINUE ACROSS THE AREA DURING THE NEXT
SEVERAL DAYS. FOR THE REST OF MAUI COUNTY AND THE BIG ISLAND...THE
WIND ADVISORY REMAINS IN EFFECT UNTIL 6 PM HST WED AS GRADIENTS IN
THAT EASTERN PORTION OF THE ISLAND CHAIN WILL REMAIN SLIGHTLY
STRONGER.

A MID/UPPER LVL LOW/TROUGH COMPLEX REMAINS SOME 500 MILES E/NE OF
THE BIG ISLAND WITH AN AXIS EXTENDING INTO MAUI AND THE BIG ISLAND.
THIS SYSTEM WILL SLOWLY MOVES N/NE DURING THE NEXT COUPLE OF DAYS
WITH ITS AXIS LINGERING AROUND THE ISLANDS. THEN THE MID LVL LOW
GRADUALLY MIGRATES W AND CLOSER TO THE ISLANDS BY SAT...BRINGING
INCREASING INSTABILITY. THIS WILL ENHANCE THE TRADE WIND SHOWERS
DURING THE WEEKEND. STILL EXPECTING THE BULK OF THE RAIN TO FAVOR
WINDWARD AND MAUKA...BTU THE WINDS WILL REMAIN STRONG ENOUGH TO
PUSH SOME OF THE LARGER SHOWERS INTO LEEWARD LOCATIONS AT TIMES.

CONDITIONS BECAME A LITTLE DRIER TODAY WITH WEAK INVERSIONS AND A
SLIGHTLY MORE STABLE AIRMASS ESTABLISHING ACROSS THE AREA...BUT
ADDITIONAL MOISTURE UPSTREAM AND THE GRADUAL EROSION OF THE
INVERSIONS WILL ALLOW FOR ANOTHER WETTER TREND TO BEGIN TONIGHT. THE
WEAK AND MORE ELEVATED INVERSIONS WILL ALLOW FOR CLOUDS AND SHOWERS
TO REACH THE BIG ISLAND SUMMITS TONIGHT...BRINGING A CHANCE FOR
FREEZING RAIN. A WINTER WEATHER ADVISORY WILL BE IN EFFECT FROM 10
AM HST TONIGHT THROUGH 10 AM HST WED.

THE WETTER TRADE WIND REGIME WILL CONTINUE THROUGH THE REST OF THE
WEEK...AND BECOMING EVEN MORE ACTIVE FOR THE WEEKEND AS THE
AFOREMENTIONED MID LVL LOW MOVES CLOSER TO THE MAIN HAWAIIAN
ISLANDS. TRADE SPEEDS REMAIN STRONG THROUGH THU...THEN GRADUALLY
SUBSIDING DURING THE WEEKEND.

&&

.AVIATION...
VFR CONDITIONS ARE EXPECTED TO CONTINUE OVER THE NEXT 24 HOURS WITH
ISOL MVFR/IFR POSSIBLE FOR WINDWARD AREAS...ESPECIALLY FOR BIG
ISLAND. ISOLATED SHOWERS WITH BRIEF MVFR CONDITIONS MAY STRAY INTO
LEEWARD AREAS OVERNIGHT AND INTO THE EARLY MORNING HOURS.

AIRMET TANGO CONTINUES FOR LLVL TURB AND STRONG SUSTAINED SFC WINDS
ACROSS THE ISLANDS AS THE PRESSURE GRADIENT REMAINS STRONG. LITTLE
CHANGE TO THIS SCENARIO IS ANTICIPATED THROUGH WEDNESDAY AFTERNOON.

&&

.MARINE...
A GALE WARNING REMAINS IN EFFECT UNTIL THU 6 SM HST FOR THE TYPICAL
WINDIER WATERS NEAR MAUI COUNTY AND THE BIG ISLAND. ALSO...A SMALL
CRAFT ADVISORY REMAINS IN EFFECT THROUGH THE SAME TIME PERIOD FOR
THE REST OF THE WATERS DUE TO STRONG WINDS AND ROUGH SEAS.

A HIGH SURF ADVISORY REMAINS UP FOR MOST EAST FACING SHORES DUE TO
STRONG TRADES...ALSO THROUGH 6 AM HST THU. OTHERWISE...ONLY
A SMALL NW SWELL IS EXPECTED THROUGH THE REST OF THE WEEK.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY UNTIL 6 AM HST THURSDAY FOR EAST FACING SHORES
OF KAUAI OAHU MOLOKAI MAUI AND BIG ISLAND.

WIND ADVISORY UNTIL 6 PM HST WEDNESDAY FOR LANAI-KAHOOLAWE-MAUI-
SOUTH BIG ISLAND-BIG ISLAND NORTH AND EAST-KOHALA-BIG ISLAND
INTERIOR.

WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 10 AM HST
WEDNESDAY FOR BIG ISLAND SUMMITS.

GALE WARNING UNTIL 6 AM HST THURSDAY FOR MAALAEA BAY-PAILOLO
CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND LEEWARD WATERS-BIG ISLAND
SOUTHEAST WATERS.

SMALL CRAFT ADVISORY UNTIL 6 AM HST THURSDAY FOR ALL OTHER
HAWAIIAN COASTAL WATERS NOT IN THE GALE WARNING.

&&

DISCUSSION/MARINE...REYNES
AVIATION...LUTU-MCMOORE